E79 issue

[Robslocum]

E79 code on nest learning thermostat.  Have 24V between red and common.  But is says no power to C Wire.   I already cleaned and re wired many times and the thermostat still shows the wire but does not show power?  
What else can be done?   

[David_K]

The E79 error does indeed mean no power to the C wire is being detected. If you've got two switches in your breaker or fuse box, one for heating and one for cooling, make sure the power is on for both as I've seen that be an issue before.

It sounds like you've already tried things like checking the wires are correctly inserted, that every connector with a wire is down and that each wire has ⅜ inch (6mm) of exposed wire. 

As you’ve completed those steps and your thermostat still isn’t working correctly, I'd recommend contacting a local pro for more help.

[Ryan_G]

Hi Robslocum,

Thanks for reaching out here in the community.

I'd like to jump in here and check if you've seen davidking's response about the E79 error. If you have any other questions, let us know by replying to this thread.

Thanks for the help, davidking.

Best regards,

Ryan

[Ryan_G]

Hey Robslocum,

I just wanted to follow up and see if you're still in need of help. Please let us know as we would be happy to answer any questions you may have. 

Best regards,

Ryan

[Ryan_G]

Hey there,

Thanks for being here in the Google Nest Community. 

I'd like to bump in here and make sure that you’ve seen our response.

Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.

Have a great day.

Best regards,

Ryan